Monitoring & metering T
ypically, the mains-powered water quality analysers that are used for process monitoring at wastewater treatment works (WwTW) deliver accurate, high-quality data, but they have a significant footprint and are costly to install and operate. As
a consequence, they only tend to be deployed at larger sites. However, in recent years it has become evident that final effluent can also be monitored with the same technologies that are used to monitor rivers. These ESNET systems are particularly advantageous for final effluent monitoring for a number of reasons. A single ESNET system, for example, is able to monitor multiple parameters simultaneously, providing almost real-time data from even the most remote sites. Importantly, in comparison with traditional final effluent monitors, ESNETs are quick, easy and low-cost to install and operate. However, as this article will explain, the connectivity of the ESNET units can be exploited to dramatically enhance process control.
ESNET DEPLOYMENTS AT SCOTTISH WATER
In 2021, Scottish Water started to install ESNET remote water quality monitors at some of its urban WwTWs. “The ESNET systems have dramatically improved our visibility of final effluent water quality data, without having to implement significant capital works,” explains Jamie Hesketh, process science leader at Scottish Water. “Since 2021, we have installed 67 of the kiosk-based ESNET systems as final effluent monitors, and they have been so successful that we now plan to install around 113 more systems over the next few years.”
The kiosk-based systems have been installed at urban WwTW sites with a population equivalent of 2000 or above, but this may be expanded to PE>1000 as the rollout takes place. An automatic sampler was previously deployed at most of these sites, collecting final effluent samples that are stored and collected for subsequent analysis in a laboratory. The advantage of this method is that the samples can be tested for a wide variety of parameters, but the major disadvantage is the delay incurred by this procedure, which prevents automation and severely limits opportunities for process control. Consequently, processes such as dosing tend to operate 24/7 rather than on an ‘as required’ basis.
WHAT IS AN ESNET?
Developed and manufactured by Meteor Communications, ESNET systems are complete, stand-alone, multi-parameter remote water quality monitors. Originally designed for installation at sites with limited or no services, there are now hundreds of ESNET stations operating all over the UK, delivering almost real-time data from a wide
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FINAL EFFLUENT MONITORS ENABLE SUBSTANTIAL EFFICIENCIES AT SCOTTISH WATER
In the following article, Tim Wilson from Meteor Communications explains how, in addition to providing visibility of water quality, final effluent monitors known as ESNET are also delivering substantial benefits for Scottish Water through enhanced process control. For example, the ESNET units are dramatically reducing the use of dosing chemicals by introducing automatic monitoring and control.
August 2025 Instrumentation Monthly
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